This invention relates generally to antennas, and more particularly to an apparatus and method for dampening low frequency vibrations associated with the use of telematic antennas on motor vehicles.
Over the past few decades, automobile technology has improved dramatically, particularly in the areas of consumer comfort, convenience, and safety. As automobile manufacturers continually strive to make automobiles more comfortable for passengers, a key area of concern is the level of noise and vibration present within passenger compartments. Many factors contribute to these noise and vibration levels, including the mounting of the engine, the nature of any insulation within the engine compartment, the type and balancing of the tires, and the ability for wind to pass freely over the external profile of the automobile. Such factors are thus carefully designed so as to ensure the most comfortable environment possible within the passenger compartment.
One example of a device that affects the ability for wind to pass freely over the external profile of an automobile is an antenna used for wireless communications. When such an antenna is present upon the external profile of an automobile, wind resistance is generated and a discernable noise and/or vibration may resultantly develop when the automobile travels at high rates of speed or is otherwise subject to strong winds. This noise and/or vibration is often detectable and might prove annoying or distracting to persons within the automobile""s passenger compartment (hereafter xe2x80x9coccupantsxe2x80x9d). As a result, this generation of noise and/or vibration may resultantly prevent the occupants from enjoying the very communications that such antennas were designed to facilitate.
The type of noise and/or vibration generated by an antenna depends in large part upon the antenna""s shape. Although there are now many shapes of antennas being used on automobiles, perhaps the most common antenna traditionally used has a rod-shape. A rod-shaped antenna is typically relatively long and quite slender, and is often referred to as a xe2x80x9cmastxe2x80x9d antenna. For example, an automobile""s AM/FM radio antenna is typically a rod-shaped antenna having a length of between about 0.3 meters and about 1 meter and a diameter of less than about 10 millimeters. Some rod-shaped antennas might also include a phase coil disposed along the rod.
Certain rod-shaped antennas have been identified as generating high frequency whistling noises, such as in the 1,000 Hz to 10,000 Hz range, when the antenna is attached to an automobile moving at high speeds or is otherwise subject to strong winds. These whistling noises are said to interfere with occupants"" comfort within the automobile, particularly with regard to such activities as cellular telephone conversations. Various patents have disclosed structures for eliminating this whistling noise. For example, Taguchi (U.S. Pat. No. 5,151,711) teaches the addition to a rod-shaped antenna of a hollow cylindrical member including a plurality of hollow cylindrical units, wherein the cylindrical member has one or more ridges to generate a turbulent flow of air around the antenna and resultantly eliminate the high frequency whistling caused by strong winds. However, such patents are deficient in many areas, particularly with regard to eliminating different types of wind noises, such as those created by antennas not having the traditional rod-shape.
As technological advances in wireless automotive communication systems continually progress, antennas not having the traditional rod-shape are becoming more commonplace. For example, because many of these recent advances, such as the Global Positioning System (xe2x80x9cGPSxe2x80x9d), satellite radio, and advanced cellular (e.g.: wireless) telephones, typically transmit and receive relatively high frequency digital radio waves having correspondingly short wavelengths, these systems are able to effectively communicate using considerably shorter antennas than those rod-shaped antennas traditionally used by other less sophisticated communication systems. One such alternative to the traditional rod-shaped antenna involves an antenna incorporating an extremely short but relatively wide shaft, wherein the overall length of the shaft is less than about ten times the diameter of the shaft, hence giving the antenna a xe2x80x9cfinger-shapexe2x80x9d. Because of its unique configuration, the finger-shaped antenna does not typically generate the high frequency whistling noises that are typically associated with rod-shaped antennas when subjected to strong winds. Rather, the finger-shaped antennas often generate an equally annoying and disturbing low frequency vibration when subjected to strong winds. Because rod-shaped antennas tend to whistle at high frequencies rather than vibrate at low frequencies, and because finger-shaped antennas are physically quite different from rod-shaped antennas, a creative solution is necessary to dampen the low frequency vibrations common to finger-shaped antennas. Although the shafts of some finger-shaped telematic antennas have been modified to include indentations such as grooves, slots, dimples, or the like, presumably for aesthetic purposes, none of these prior art designs functions to reduce low frequency vibrations. To the contrary, such designs generate even greater amplitudes of low frequency vibrations when subjected to strong winds. It is for these reasons that the solution of the present invention has come to light.
In accordance with the present invention, a finger-shaped antenna is affixed to an exterior surface of an automobile. The shaft of the finger-shaped antenna is fitted with one or more turbulence generators specifically configured and arranged to dampen any low frequency vibrations that would otherwise be generated by the antenna when exposed to strong winds. The one or more turbulence generators can, in one embodiment of the present invention, constitute an outwardly directed protrusion from the outer surface of the shaft, wherein the protrusion extends helically in a direction generally parallel to the longitudinal axis of the shaft. This protrusion is operable to generate air turbulence and resultantly dampen the problematic low frequency vibrations of the finger-shaped antenna. The present invention therefore enables the use of the finger-shaped antenna, and accordingly any associated communication devices, without any adverse impact on the comfort of the automobile""s occupants.
The present invention is not limited to the finger-shaped antenna, but is equally applicable to a multitude of other antennas or objects that generate noise and/or vibrations when exposed to strong winds, such as those winds present surrounding an exterior surface of an automobile, truck, aircraft, motorcycle, all terrain vehicle (xe2x80x9cATVxe2x80x9d), watercraft, building, or other such location. Furthermore, the present invention relates not only to antennas for GPS, satellite radio, and advanced cellular telephones, but also to antennas for any other type of communication system.
Accordingly, it is an object of the present invention to reduce low frequency vibrations associated with the use of telematic antennas on motor vehicles.
Additional objects, advantages, and novel features of the invention will be set forth in part in the description that follows and in part will become apparent to those skilled in the art upon examination of the following or may be learned with the practice of the invention. The objects and advantages of the invention may be realized and attained by means of the instrumentalities and combinations particularly pointed out in the appended claims.
To achieve the foregoing and other objects, and in accordance with the purposes of the present invention defined herein, an apparatus and method is provided for enabling the dampening of low frequency vibrations associated with telematic antennas on motor vehicles. The telematic antenna with low frequency dampening for use on a motor vehicle comprises a shaft adapted to be mounted on a vehicle, the shaft having a longitudinal axis and an outer surface, the outer surface having a configuration that surrounds and extends generally parallel to the longitudinal axis, wherein the diameter of the configuration defines the diameter of the shaft. The antenna further comprises a conductor, the conductor substantially enclosed by the outer surface, and an air turbulence generator in contact with the outer surface for dampening vibrations transmitted to a vehicle by the shaft, the air turbulence generator extending helically in a direction generally parallel to the longitudinal axis, and the air turbulence generator extending radially outwardly from the outer surface of the shaft by a distance greater than or equal to about 10% of the diameter of the shaft.
In accordance with one aspect of the invention, the air turbulence generator extends radially outwardly from the outer surface of the shaft by a distance between about 10% and about 20% of the diameter of the shaft.
In another aspect of the invention, the air turbulence generator extends radially outwardly from the outer surface of the shaft by a distance of about 10% of the diameter of the shaft.
In yet another aspect of the invention, the air turbulence generator extends substantially continuously along the shaft.
In accordance with still a further aspect of the invention, the cross-sectional diameter of the air turbulence generator in a direction normal to the radial extension of the air turbulence generator and normal to the helical extension of the air turbulence generator is substantially equal to the distance of radial extension by the air turbulence generator outward from the shaft.
In still another aspect of the invention, the helical projection of the air turbulence generator defines a plurality of windings of the air turbulence generator around the shaft, wherein the distance between the cross-sectional centers of two adjacent windings defines the pitch.
In yet another aspect of the invention, the pitch is substantially uniform among all adjacent windings of the air turbulence generator.
In accordance with another aspect of the invention, the pitch is between about 5 millimeters and about 10 millimeters.
In accordance with still another aspect of the invention, the pitch is about 5 millimeters.
In a further aspect of the invention, the air turbulence generator is integral with the shaft.
In still a further aspect of the invention, the configuration is generally cylindrical.
In accordance with yet another aspect of the invention, the air turbulence generator is electrically isolated from the conductor.
In another aspect of the invention, the air turbulence generator is operative to reduce vibrations having a frequency less than about 1000 Hz.
In yet another aspect of the invention, the air turbulence generator is operative to reduce vibrations having a frequency between about 200 Hz and about 500 Hz.
In accordance with yet a further aspect of the invention, the air turbulence generator is operative to reduce vibrations having a frequency between about 300 Hz and about 400 Hz.
In accordance with another specific aspect of the invention, the air turbulence generator is operative to reduce vibrations having a frequency of about 315 Hz.
In yet another aspect of the invention, a method is disclosed of providing a vehicle-mounted telematic antenna having reduced wind-generated low frequency vibrations. This method comprises the steps of providing an elongated conductor that extends in a longitudinal direction, enclosing the conductor with a shaft, providing an air turbulence generator in the form of a helical protrusion that extends outwardly from the outer surface of the shaft by a distance approximately equal to about 10% to about 20% of the diameter of the shaft, helically extending the protrusion continuously along the outer surface of the shaft in a direction generally parallel to the longitudinal direction, and providing a mounting for securing the shaft to a vehicle.
In still another aspect of the invention, the step of providing the air turbulence generator involves extending the protrusion radially outwardly from the shaft a distance equal to about 10% of the diameter of the shaft.
In yet a further aspect of the invention, the method further comprises the step of fastening the air turbulence generator to the outer surface of the shaft.
In accordance with another aspect of the invention, the air turbulence generator is provided having a substantially circular cross-sectional configuration.
In yet another aspect of the invention, the helical protrusion is integrally formed with the shaft.
In another aspect of the invention, a telematic antenna with low frequency dampening for use on a motor vehicle comprises a shaft adapted to be mounted on a vehicle, the shaft having a longitudinal axis and an outer surface, the outer surface having a configuration that surrounds and extends generally parallel to the longitudinal axis, wherein the diameter of the configuration defines the diameter of the shaft. The antenna further comprises a conductor, the conductor being substantially enclosed by the outer surface, wherein the air turbulence generator is electrically isolated from the conductor. Also comprised is an air turbulence generator in contact with the outer surface of the shaft, the air turbulence generator extending substantially continuously and helically in a direction generally parallel to the longitudinal axis, and the air turbulence generator extending radially outwardly from the outer surface of the shaft by a distance of about 10% of the diameter of the shaft, wherein the shaft and the air turbulence generator are formed integrally.
In accordance with still a further aspect of the invention, a combination of a motor vehicle with a telematic antenna is provided with a low frequency dampening comprising a shaft adapted to be mounted on the vehicle, the shaft having a longitudinal axis and an outer surface, the outer surface having a configuration that surrounds and extends generally parallel to the longitudinal axis, wherein the diameter of the configuration defines the diameter of the shaft. The antenna also comprises an air turbulence generator in contact with the outer surface of the shaft for dampening vibrations transmitted to a vehicle by the shaft, the air turbulence generator extending helically in a direction generally parallel to the longitudinal axis, and the air turbulence generator extending radially outwardly from the outer surface of the shaft by a distance greater than or equal to about 10% of the diameter of the shaft.